CN100465321C - Trace niobium -containing steel for cooling-control reinforced bar and method for producing same - Google Patents
Trace niobium -containing steel for cooling-control reinforced bar and method for producing same Download PDFInfo
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- CN100465321C CN100465321C CNB2005100948359A CN200510094835A CN100465321C CN 100465321 C CN100465321 C CN 100465321C CN B2005100948359 A CNB2005100948359 A CN B2005100948359A CN 200510094835 A CN200510094835 A CN 200510094835A CN 100465321 C CN100465321 C CN 100465321C
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Abstract
Steel with micro amount of Niobium used for controlled cooling steel and its production methods, belongs to the hot rolling ribbed steel used in ferroconcrete, especially steel rod with micro-niobium and its production method. The steel rod contains the following elements: (by wt. ratio): 0.15-0.25%C, 0.30-0.80%Si, 1.00-1.60%Mn, <=0.045%P, S, 0.005-0.02%Nb,<=0.0080%N, Fe as the rest and impurities elements. The production method of the steel rod contains the following steps: smelting, according to the specified elements and content, with conventional smelting method in a revolver or an electric furnace, rolling with a merchant bar mill, at temperature 1050-1220DEG C, rolling at a temperature over 950DEG C, rapidly cooling at a temperature of 800-1050,shearing, bundling, and warehousing after natural cooling. The method of the invention solves the problems of instable production process and performance, too high temperature during the heating of the steel billet, cracks in continuous casting billet and other issues.
Description
Technical field:
The invention belongs to the Steel Concrete hot-rolled reinforced bar, especially relate to the reinforcing bar and the production method thereof of trace niobium-containing.
Background technology:
At present, the HRB400 high strength cast iron of applying yield strength 400MPa level has been development trend, but the method for producing the HRB400 reinforcing bar is too single, although national standard " Steel Concrete hot rolled ribbed steel bar " (GB1499-1998) regulation can adopt micro alloying elements such as vanadium, niobium, titanium, still mainly adopt vanadium iron or VN alloy microalloying technology for a long time.Because the demand to vanadium iron and VN alloy increases considerably and vanadium iron and VN alloy resource anxiety, is unfavorable for the reasonable use of vanadium resource, also can make cost up, even have a strong impact on applying of HRB400 reinforcing bar.
In state-owned business organization manufactured experimently the 20MnTi reinforcing bar of 400MPa level, but do not have business stability ground to produce this reinforcing bar in batches so far, reason is that some agricultural technology problems also do not obtain satisfied solution.Cross when low as: titanium content, intensity is difficult to meet the demands, and titanium content easily produces during continuous casting and holds stream when higher, and the recovery rate during titanium steel-making is very low and unstable, and the performance inconsistency of reinforcing bar is big etc.
The investigator of the Ultrafine Grained Steel muscle of 400MPa level utilizes the microstructure ultra-fining treatment production technology to realize producing the 400MPa grade reinforcing steel with Q235 class straight carbon steel, has reduced alloy content significantly, does not need to add micro alloying element.But production Ultrafine Grained Steel muscle needs low temperature rolling, to having relatively high expectations of equipment, also fails at present to realize producing in enormous quantities.
Adopt waste heat treatment steel bar in addition, utilize the waste heat of Q235 class straight carbon steel or 20MnSi reinforcing bar to handle, just can produce 400MPa level, 460MPa level even 500MPa grade reinforcing steel, its ultimate principle is after to be reinforcing bar from the finished frame of milling train shut out, carrying out accelerated surface through refrigerating unit quenches, utilize reinforcing bar core heat self-tempering from inside to outside then, and at the cold bed air cooling to room temperature.This technology can effectively utilize phase transformation strengthening, brought into play the intensity potentiality of steel, but this technology is not approved in the Chinese architecture industry that at present reason is to lose strong phenomenon after the waste heat treatment steel bar welding, and think that rebar surface forms hard phase constitution, reduce the fatigue property of member.
From angle reasonable, that equilibrium utilizes resource, adopting the Nb-microalloying technology to produce the 400MPa grade reinforcing steel is to select preferably.Recommending the reference content of 20MnSiNb reinforcing bar niobium in the national standard " Steel Concrete hot rolled ribbed steel bar " (GB1499-1998) is 0.02-0.04%, in fact in order to guarantee the performance of reinforcing bar, content of niobium needs 0.03-0.05% in the general reinforcing bar, ferro-niobium in the molten steel (60%) add-on needs more than 0.05%, higher content of niobium has not only increased cost, and bring some problems, limited the production application that contains the niobium reinforcing bar, it is stable to can not show a candle to the vanadium micro-alloying reinforcing bar as its production technique and performance, for the carbonitride that guarantees niobium fully dissolves in the austenite, need higher billet heating temperature, have the unconspicuous problem of Yield Point Of Steel Bar.
Summary of the invention:
In order to overcome the defective that prior art exists, the objective of the invention is to design a kind of reinforcing bar steel and production method thereof of trace niobium-containing, guarantee the strength property of reinforcing bar by suitable controlled chilling, be starkly lower than the niobium content of present similar Nb-microalloying reinforcing bar, not only reduce cost, and solved production technique that present Nb-microalloying reinforcing bar exists and unstable properties, the too high problem of billet heating temperature well.
A kind of trace niobium-containing steel for cooling-control reinforced bar is by weight percentage by following elementary composition: 0.15-0.25%C, 0.30-0.80%Si, 1.00-1.60%Mn ,≤0.045%P ,≤0.045%S, 0.005-0.012%Nb, ≤ 0.0080%N, all the other are Fe and impurity element.
The production method of trace niobium-containing controlled cooling reinforcing bar comprises the steps: to smelt, and presses designed element and content, adopts conventional smelting process, smelts on converter or electric furnace, and continuous pouring becomes steel billet; Merchant bar mill is rolling, and billet heating temperature is controlled at 1050-1220 ℃ of scope when rolling, finish more than 950 ℃ rolling; Controlled chilling rolls the back rolled piece and cools off fast, and the temperature of cold bed is at 800-1050 ℃ on the reinforcing bar; Reinforcing bar is naturally cooling on cold bed, cooling back shearing, bundling, warehouse-in.
Specify the content of technical scheme below.
Carbon of the present invention, silicon, manganese content are suitable substantially with existing yield strength 400MPa grade reinforcing steel, and the requirement of phosphorus, sulphur impurity element is also suitable.The present invention adopts niobium as micro alloying element, and niobium mainly shows as grain refining, precipitation strength and phase transformation strengthening to the strengthening effect of reinforcing bar, and the adding of niobium is necessary.The present invention has adopted 0.005-0.012% very low content of niobium not only to reduce cost, and solved higher content of niobium and brought some problems, understable as its production technique and performance, billet heating temperature is higher, sometimes problem such as not obvious, continuously cast bloom crackle occurrence probability height of Yield Point Of Steel Bar.To nitrogen content limited mainly be for the carbon that reduces niobium, nitride solid solution in austenite temperature and separate out temperature, make that billet heating temperature needn't be too high when rolling, the more abundant strengthening effect that waits the performance niobium.
Owing to reduced content of niobium and nitrogen content is limited,, press 1050-1220 ℃ of scope and control and get final product so billet heating temperature needn't be too high when rolling.Rolling promptly finish rolling substantially in the austenite recrystallization district be in order to realize the recrystallize refinement finishing more than 950 ℃, and existing steel rolling equipment and technology realize easily.Rolling temperature is easy to generate mixed crystal in the part recrystallization zone, and performance is had a negative impact.Steel rolling equipment that rolling temperature is then existing in the non-recrystallization district and technology are difficult to realize.The loss of strength that the reduction content of niobium causes mainly remedies by austenitic cooling before quickening phase transformation, quicken cooling and help preventing that austenite crystal from growing up, the carbon, nitride that also helps suppressing niobium is separated out and is grown up middle warm area, and nucleation rate is separated out in increase, increase the effect that it stops recrystal grain to be grown up, the austenite crystal refinement has caused the structure refinement of the finished product before the phase transformation.The acceleration cooling also helps carbon, nitride is separated out at cold zone.The intensity that refined crystalline strengthening that increases and precipitation strength have improved reinforcing bar.But the last cold bed temperature of reinforcing bar must be controlled at more than 800 ℃ or more than the Ar3 temperature, is in order to prevent that too much low temperature phase change products such as bainite from appearring occurring on tempered structure and the reinforcing bar section in surface of reinforced bar.
Adopt division lines method that reinforcing bar microstructure relative quantity is measured, the result shows, the microstructure of the hot-rolled reinforced bar that the present invention produces is based on ferrite+perlite (more than 85%), and all the other also may contain a small amount of bainite tissues such as (containing granular bainite).
The controlled cooling reinforcing bar of the trace niobium-containing that the present invention produces, its performance index reach: σ
s(σ
P0.2)=400-520MPa, σ
b〉=570MPa, σ
b/ σ
s(σ
P0.2) 〉=1.25, δ
5〉=14%, clod wash d=4a, 180 ° are qualified.
Compared with prior art, the controlled cooling reinforcing bar content of niobium of trace niobium-containing reduces, functional, and solved problems such as production technique that present Nb-microalloying reinforcing bar exists and unstable properties, billet heating temperature are too high, continuously cast bloom crackle occurrence probability height well, reduced production cost.
Embodiment:
Further specify the present invention below by embodiment.Adopt conventional smelting process, smelt in converter by specified element of each specification of table 1 and content, continuous casting becomes the 150mm square billet; Adopt general continuous merchant bar mill, 1050-1250 ℃ of strict control billet heating temperature are rolling finishing more than 950 ℃; Controlled chilling rolls the cooling of the quick water-cooled of back rolled piece, and the temperature of last cold bed is controlled in 800-1050 ℃ the scope, naturally cooling on cold bed, shearing then, bundling, warehouse-in.Its processing parameter and performance are listed in the table 2.
The relative quantity of organizing the reinforcing bar sample adopts division lines method to measure under 100 times of full phase microscopes, and measurement is no less than 50 should the field.The relative quantity of organizing of reinforcing bar sample sees Table 3.
Table 1
Table 2
Table 3
| Sequence number | Ferrite+perlite (F+P) | Bainite (B) | Specification (mm) |
| 1 | 100 | 0 | ￠12 |
| 2 | 93 | 7 | ￠16 |
| 3 | 92 | 8 | ￠16 |
| 4 | 89 | 11 | ￠25 |
| 5 | 85 | 15 | ￠25 |
Claims (3)
1. the steel for cooling-control reinforced bar of trace niobium-containing is by weight percentage by following elementary composition: 0.15-0.25%C, 0.30-0.80%Si, 1.00-1.60%Mn ,≤0.045%P ,≤0.045%S0.005-0.012%Nb, ≤ 0.0080%N, all the other are Fe and impurity element.
2. produce the production method of the steel for cooling-control reinforced bar of trace niobium-containing according to claim 1, it is characterized in that may further comprise the steps composition: steel-making, by specified element and content, adopt conventional smelting process, smelting, continuous casting become steel billet on converter or electric furnace; Merchant bar mill is rolling, and billet heating temperature is controlled at 1050-1220 ℃ of scope when rolling, finish more than 950 ℃ rolling; Controlled chilling rolls the back rolled piece and cools off fast, and the temperature of cold bed is controlled at 800-1050 ℃ on the reinforcing bar; Behind the naturally cooling, shearing, bundling, warehouse-in.
3. the steel for cooling-control reinforced bar of trace niobium-containing according to claim 1, the microstructure that it is characterized in that reinforcing bar is based on ferrite+perlite, reaches more than 85%, all the other are a small amount of bainite structure.
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| CNB2005100948359A CN100465321C (en) | 2005-10-17 | 2005-10-17 | Trace niobium -containing steel for cooling-control reinforced bar and method for producing same |
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| CNB2005100948359A CN100465321C (en) | 2005-10-17 | 2005-10-17 | Trace niobium -containing steel for cooling-control reinforced bar and method for producing same |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111549289A (en) * | 2020-06-19 | 2020-08-18 | 阳春新钢铁有限责任公司 | Ultra-high pulling speed niobium-containing HRB400E deformed steel bar and production process thereof |
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| CN102653834B (en) * | 2012-05-04 | 2014-11-26 | 武汉钢铁(集团)公司 | Circular chain steel and production method thereof |
| CN102747274A (en) * | 2012-07-13 | 2012-10-24 | 江苏永钢集团有限公司 | Vanadium-boron microalloyed waste heat treatment reinforced bar steel and production technique thereof |
| CN104233075A (en) * | 2013-11-13 | 2014-12-24 | 马钢(集团)控股有限公司 | Chromium-containing niobium microalloyed 400MPa-grade reinforcing bar steel and production method thereof |
| CN104233074A (en) * | 2013-11-13 | 2014-12-24 | 马钢(集团)控股有限公司 | Steel for chromium-containing vanadium-nitrogen micro-alloyed 400MPa level reinforcing steel bar and production method thereof |
| CN107815525A (en) * | 2017-11-30 | 2018-03-20 | 攀钢集团攀枝花钢铁研究院有限公司 | Microalloy containing Nb builds steel wire rod and its production method |
| CN110819892A (en) * | 2019-10-14 | 2020-02-21 | 长沙东鑫环保材料有限责任公司 | Niobium-nitrogen-containing microalloyed HRB400E steel bar and production method thereof |
| CN110747396A (en) * | 2019-10-30 | 2020-02-04 | 广东韶钢松山股份有限公司 | Niobium microalloyed HRB400E hot-rolled ribbed steel bar and efficient manufacturing method thereof |
| CN111014287B (en) * | 2019-12-23 | 2021-10-01 | 新疆八一钢铁股份有限公司 | Production method of niobium-containing ribbed steel bar |
| CN111074157B (en) * | 2020-01-11 | 2021-05-18 | 武钢集团昆明钢铁股份有限公司 | Low-niobium microalloyed HRB400E ultrafine-grain high-toughness anti-seismic steel bar and preparation method thereof |
| CN111235478A (en) * | 2020-03-16 | 2020-06-05 | 阳春新钢铁有限责任公司 | Low-niobium HRB400E coiled steel and production method thereof |
| CN112387790B (en) * | 2020-10-29 | 2022-07-08 | 江苏沙钢集团有限公司 | Production process of micro-niobium alloyed disc spiral HRB400 and HRB400E |
| CN113042525B (en) * | 2021-02-24 | 2023-04-07 | 广西柳钢华创科技研发有限公司 | Method for increasing thickness of iron scale on surface of high-speed bar and production method of HRB400E straight threaded steel bar |
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| CN111549289A (en) * | 2020-06-19 | 2020-08-18 | 阳春新钢铁有限责任公司 | Ultra-high pulling speed niobium-containing HRB400E deformed steel bar and production process thereof |
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